It is common practice in the machine tool industry to use abrading tools to finish the walls (e.g., removing about 0.001 to 0.005 inches of material) of a previously provided bole or similar interior surface of a workpiece. Abrading operations generally correct inaccuracies in straightness and roundness in bore holes, can provide a uniform hole surfaces, or can remove burrs or finish surfaces.
A number of abrading devices have been developed to abrade, finish, polish or grind workpiece holes. U.S. Pat. No. 6,152,814 issued Nov. 28, 2000 describes an expandable abrasive sleeve for use on an inflatable tool to abrade or condition a surface of a workpiece. The expandable abrasive sleeve comprises an elastomeric backing, for example, made of a rubber material, and a plurality of separate abrasive strips adhered to the elastomeric backing in an overlapping relationship such that the strips overlap when the sleeve is expanded. The expandable abrasive sleeve is disposed around an inflatable bladder and inserted with a bore to be abraded. The sleeve is then inflated, causing it to expand until it bears against the inner walls of the bore, and rotated to abrade the inner wall.
Although this inflatable sleeve successfully abrades the inner walls of the bore, this system has a number of serious drawbacks. First, the diameter of the bore to be abraded is both uncontrollable and non-uniform. Because of the sleeve is necessarily made of a relatively pliable elastomeric material, the sleeve it does not maintain a uniform diameter and tends both to flare out the exposed ends of the bore and under-abrade areas within the bore. Second, an inflated sleeve cannot be inserted into the bore and, therefore, the tool is not readily adapted for abrading chamfers or anything less than an entire bore. Finally, the sleeve and tool system are relatively expensive. The tool requires a source of compressed air proximate to the workpiece to be abraded, requiring a significant upfront investment. Further, the inflatable sleeve requires laborious fabrication due to the process of attaching the abrading material. Each piece of abrading material must be adhered onto the tool one at a time. This burdensome process guarantees a high price for a tool that must be discarded after use.
U.S. Pat. No. 5,672,096 issued Sep. 30, 1997 describes an inflatable tool for abrading or finishing a surface of a workpiece. The inflatable tool includes an inflatable bladder clamped at first and second ends of a core having an elastomeric outer core portion. The inflatable bladder is inflated by a pressurized medium and forms a pocket or chamber around the elastomeric outer core portion. An abrasive sleeve is disposed around and secured by the inflatable bladder when inflated.
While this invention allows a tool to be inflated to various sizes and to chamfer, its lack of uniformity creates a serious drawback. The diameter is uncontrollable. This lack of diameter variance only allows a craftsman to abrade holes at a preset diameter controlled by the manufacturer. Furthermore, this tool hardly stands alone; it requires an air mandrel to expand the sleeve in order to abrade. This could be a significant upfront investment.
U.S. Pat. No. 3,232,011 issued Feb. 1, 1966 describes a pneumatically actuated expanding tool for grinding, polishing, and lapping tubing inside diameters or cylindrical bores. The tool employs abrasive cloth or paper which may be inserted into a tube or the like, and expanded to provide a controlled radial force or pressure on the inner surface of the tube while the tool is linearly advanced and retracted and/or rotated or oscillated back and forth about its longitudinal axis. Means are also provided for blowing air through the tool to cool it and to exhaust particles of abrasive dust from a tube in which the tool is employed.
Although this tool expands to grind and polish a hole, any expansion is unmeasurable. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Aside from this, any expansion requires another instrument to pneumatically pressurize the tool.
U.S. Pat. No. 2,605,594 issued Aug. 5, 1952 describes a pneumatically inflatable abrasive cylinder disposed at an opposite end from a hand pump. Squeezing the pump forces air into the cylinder causing it to expand. Sandpaper is wrapped around the cylinder. To abrade, the machinist inserts the cylinder into a hole, inflates, and radially rotates the cylinder by hand.
Although this tool is certainly cost-effective, using sandpaper and no external tools, it potency is highly suspect. First, to be productively relevant, an abrading machine requires a means for fastening itself to drill or similar machine. Wrist power might be acceptable when dealing with wood, but time and work efficiency demands more power when dealing with metal. Second, as a cylinder this tool is incapable of chamfering. Third, any expansion is immeasurable.
U.S. Pat. No. 5,800,252 issued Sep. 1, 1998 describes an abrading device extending from a tool mandrel connected in a cantilevered arrangement to a machine for rotating machining operations. A rigid honing member is secured to the tool mandrel, and configured such that the effective diameter of the substantially rigid abrasive outer surface of the honing member can be uniformly and precisely varied in a radial direction relative to the longitudinal axis of the tool in response to pressure on the interior surface of the honing member. A fluid distribution system formed in the tool mandrel in a predetermined arrangement is in fluid communication with the source of pressurized fluid, and includes a pressure chamber that is configured to apply fluid pressure to the interior surface of the honing member. At least one passage extends through the honing member from the pressure chamber and has an opening on the exterior surface of the honing member for delivering fluid to dissipate heat energy and remove debris.
While this invention may effectively solve some problems associated with debris removal and precise pressurization, it still requires a tool mandrel to pressurize internal fluid in order to expand. Despite any increase in precision associated with this invention, there is no method on the tool itself to measure the bore diameter. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. As this invention expands after entry into a previously bore hole, it is incapable of chamfering.
U.S. Pat. No. 6,083,086 issued Jul. 4, 2000 describes an expanding device for grinding sleeves. The device has a cylindrical member with an outer surface, an interior chamber, an expanding chamber, and a locking mechanism. The outer surface receives the grinding sleeve, the interior chamber receives a rotatable shaft, and the expanding chamber comprises an expanding material, illustratively water, rubber, polyethylene and other known expandable polymers water-based solutions and oil-based solutions, that expands and contracts based upon pressure applied by use of a locking mechanism. The grinding sleeve can be sandpaper, diamond, emery cloth or any conventional material that grinds metal, wood, or plastic materials.
Although this grinding device allows cost-effective and simple replacements due to the use of conventional sand paper, the ability to control the diameter to an easily measurable degree is still absent. The invention works by using numerous expanding surfaces and diameters, in conjunction with liquid solutions. Using liquids in this manner of pressurizing is an improvement over previous air-pressure and liquid-pressure tools. This tool requires no external apparatus for pressurization. While this tool expands without use of a hand tool or mandrel, all the elaborate intricacies involved in the expansion ensure a hefty tool price. Also, this tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials.
U.S. Pat. No. 6,203,410 issued Mar. 10, 2001 describes a reamer with adjustable expansion/contraction and a bore finishing section comprising the reamer. The grinding section is cylindrically shaped, and has a plurality of axially-extending slits in its peripheral wall and a tapered inner surface. The rotation shaft is connected via threaded sections to a sliding shaft, which is in turn connected to a diameter expansion member consisting of a tapered cone fitted into the tapered inner surface of the grinding section. When the rotation shaft is operated to rotate, the rotational motion is converted into linear motion of the slide shaft due to a guide pin and a guide hole. The linear motion moves the diameter expansion member back and forth inside the grinding section, thereby contracting/expanding the outer diameter of the grinding section mechanically and precisely.
Although this tool's diameter expands or contracts by rotating a member located on its top, instead of using a pressurized medium, this expanded/contracted diameter is not measurable by the tool. The abrading material mentioned, diamond grindstone, is electrically deposited onto the tool. This expensive material combined with the fact that it is permanently attached to the tool, makes the tool's reusability impractical. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Furthermore, this cylindrical tool is incapable of chamfering.
Although this grinding device allows cost-effective and simple replacements due to the use of conventional sand paper, the ability to control the diameter to an easily measurable degree is still absent. The invention works by using numerous expanding surfaces and diameters, in conjunction with liquid solutions. While this tool expands without use of a hand tool, the elaborate expansion devices ensure a hefty tool price. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials.
U.S. Pat. No. 5,390,448 issued Feb. 21, 1995 describes a modular expandable honing tool or mandrel, which is adjustable within limits during a honing operation. The modular tubular honing assembly includes a drive member for attaching to a typical honing machine, a cage member adaptable for slidably receiving the abrasive sleeve member, and a retainer member for holding the abrasive sleeve member in operative position within the cage member. The abrasive sleeve member has inner and outer surfaces, the inner surface being conically tapered over its entire length while its outer surface includes a plurality of circumferentially spaced longitudinal projections positioned adjacent longitudinal channels, each projection including a honing surface having abrasive particles located thereon. The abrasive sleeve member also includes an elongated slot extending along its entire length on one side thereof which enables such member to uniformly radially expand and contract when the expander member is axially moved therethrough, the expander member having at least a portion of its outer surface which extends through the abrasive sleeve member likewise tapered at the same conical taper rate as the taper associated with the inner surface of the abrasive sleeve member for making surface-to-surface contact with the tapered inner surface of the abrasive sleeve member. Axial movement of the expander member within the abrasive sleeve member changes the diameter of the sleeve member uniformly along its entire length during a honing operation.
While this invention allows for expansion of the tool's circumference, this expansion must occur during the abrading process. The honing surfaces require must be coated or plated with an abrasive material, instead of using a simple sleeve or sandpaper. There is no gauge to indicate precise measurement. As a primarily honing tool, this tool could not abrade delicate surfaces or non-uniform holes. Furthermore, due to its cylindrical shape, this tool is incapable of chamfering.
U.S. Pat. No. 5,155,944 issued Oct. 20, 1992 describes a device for honing a workpiece surface to be machined to provide a finished size and surface configuration comprising a honing tool with adjustable honing elements, the elements having a cutting zone and a calibrating zone, and also, comprising a guide element with a surface sized to the finished size of the workpiece surface such that on the cutting stroke of the tool the cutting zone performs the cut and the tool is guided by the movement of the calibrated zone through the guide element and the abraded surface.
While this tool can manually adjust its diameter, this adjustment exists to compensate for abrasive deterioration. Any adjustments, which are minute, are neither readily measurable nor designed to allow an operator to work with holes of differing sizes.
U.S. Pat. No. 5,088,237 issued Feb. 18, 1992 describes a honing tool for machining a workpiece bore in one working stroke with honing coatings set in fixed manner to the desired size of the bore, has on a non-adjustable part of the tool body and preferably in the vicinity of a guide zone, air measuring nozzles. During the tool return stroke, these nozzles are subject to an action through the bore and measure the final size of the latter following the working zone. Optionally a readjustment can be automatically initiated as a function of the result via an adjustable body. The adjusting body is adjustable in its axial position by an adjusting device. It comprises a threaded bolt, which is rotatable by means of a hexagonal rod and moves the adjusting body in conjunction with a thread in the tool body. The tool body is circumferentially provided with five slots, which extend radially outwards from its bore and in which are guided honing strip or ledge carriers, which are covered on their outside by abrasive coatings. The honing strip carriers beveled on their inside corresponding to the conical bevel are pressed against the same by two tubular springs.
While this tool allows accurate measurement, it measures the hole after the abrasion is finished. This measurement purely exists to check accuracy, not to allow a machinist with the same tool to finish another differently sized hole. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Furthermore, the abrasion is a part of the tool, requiring that the entire tool be discarded after significant abrasion-wear.
U.S. Pat. No. 3,861,091 issued Jan. 21, 1975 describes an internal honing tool that includes a tool body which has an outer periphery and a plurality of circumferentially spaced recesses therein. The recesses include first and second portions and extend through the outer periphery of the tool body. Abrasive members are mounted in the first portions of each of the recesses and extend outwardly beyond the outer periphery of the tool body for honing a work piece. Securing members removably secure guides and abrasive stones to the tool body. The structure avoids wear of the tool body while only the abrasive members and guide members require replacement.
Although this invention allows a machinist to replace the abrasives instead of the entire tool, the tool is overly complicated and replacing the abrasives is inconvenient. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. This attribute is designed to only prevent wear and in no way accurately expands or contracts the grinding diameter.
U.S. Pat. No. 4,065,881 issued Jan. 3, 1978 describes a generally cylindrical honing tool for internally honing a workpiece which may have an interrupted bore. It has plurality of radially disposed axially extending tool supported thermoplastic guide members for engaging the workpiece at a first relatively constant pressure to aid in aligning the tool with the workpiece and having a plurality of radially disposed axially extending tool supported abrasive elements for engaging the workpiece at a pressure which is variable and independent of the guide pressure for abrading material from the workpiece.
Although this invention allows the grinding section of the tool to expand, any expansion is immeasurable. This machine is designed to extend its abrasives after insertion into a hole. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. It uses embedded grinding blocks instead of inexpensive sandpaper.
U.S. Pat. No. 3,166,876 issued Jan. 26, 1965 describes a coated abrasive construction adapted to be formed into a variety of abrading or polishing implements. It is capable of conforming to various contours and adjusting to various diameter openings. An abrasive band is mounted upon an expandable rubber mandrel which is adapted to be rotated by a suitable power source. Fixing the free end of the device at the desired degree of expansion can control the degree of expansion. This can be done permanently with the use of appropriate mandrels of temporarily by use of tape, threaded mandrels with an adjusting nut or by such other means as desired.
Although this tool uses inexpensive, although specialized, sandpaper as an abrasive means, the method of expansion is entirely impractical. No consideration is given for means to expand or contract the rubber implement, instead the machinist forces the rubber to contort and locks it into place. Next, the shape of the machine necessitates that sandpaper be cut into small, joined strips. During honing these small strips are not in sufficient contact with a support surface to effectively abrade. Using centrifugal force to expand an abrasive against an interior surface of a hole will frequently be inadequate. Also, these individual strands of sandpaper are more delicate than many jobs will require. Finally, any expansion is immeasurable.
Specialized sandpaper known as cloth stars exist to lightly grind the interior of tubing. This type of sandpaper consists of two sheets of sandpaper, each with multiple rectangular protruding blades, fastened to each other so that the rear sheet's blades fill any voids caused by the front sheet's blade gaps. Generally, a threaded metal plate fastens these two sheets.
While this type of sandpaper fits into a tube, it is wholly inadequate to expand or chamfer a hole. This paper is also restricted in the types of materials and shapes that it may sand, as the exposed edges on the front sheet of the star tend to catch on most non-uniform surfaces causing the edges to bend against the direction of radial motion exposing the non-abrading rear surface of the sandpaper to a workpiece. In addition, the use of multiple sheets of sandpaper makes these stars relatively stiff and unsuited to freely conform to the inside surfaces of bores. Finally, as a metal fastener must mechanically join the two pieces of specially cut sandpaper, the cost of these stars tends to be relatively high.
Therefore, there is a need for a tool that expands without the use of pressurizing material (liquids, air, etc.) and the machines inevitably required to administer and measure such material, that uses an inexpensive, easily replaceable material such as sandpaper, that can set its diameter before engaging a hole and hold the size to be abraded, that can chamfer a hole, that creates uniform diameters, that is versatile enough to engage hole of differing diameters, that abrades non-uniform holes, that can be extended to abrade surfaces of deep holes, that abrades delicate or thin materials, that can abrade hardened steel, that can be attached to a drill or similar apparatus, that can abrade soft or elastic materials, such as rubber. Finally, there is a need for an abrasive star that can abrade non-uniform surfaces in the interior of a tubular surface without catching.